John Keller, whom Block introduced in Hit Man, is a killer for hire, with a difference. He's thoughtful, even broody, tends to take a liking to some of the towns where he goes to do his work, dreams of perhaps settling down in one of them one day and collects stamps in his spare time, of which there's plenty. It's a novel idea, and it carried an excellent group of stories in the previous book. A whole novel about Keller, however, who after all walks a very delicate line between likability and horror, is more than he can readily bear, and, almost unknown in Block's work, there are longueurs here. The plot is wryly serviceable--a rival is attempting to corner the market by getting to some of Keller's intended victims first, and clearly has to be disposed of--but about halfway through a certain unease creeps in and won't let go. For all Block's usual great skill with goofy dialogue (here between Keller and Dot, the intermediary who takes the orders for his jobs), it's difficult to indefinitely enjoy jokes about the violent deaths of a number of people who, for all Dot and Keller know, are harmless, perhaps even good citizens, but whom someone is willing to pay to remove. Apparently mindful of this, Block keeps the killings mostly offstage, or with a minimum of graphic violence. But an affection for Keller is an acquired taste, and here it proves difficult to acquire. 9-city author tour. (Nov.)